The major objective of this project is to study the mechanism(s) involved in the metabolic activation of the urinary bladder carcinogen N-butyl-N-(4-hydroxybutyl)nitrosamine (BHBN) and its principal urinary metabolite N-butyl-N-(3-carboxypropyl)nitrosamine (BCPN). Present work involves determination of the effect of disulfiram (DSF) on the carcinogenicity and metabolism of BHBN and BCPN in male Wistar rats. DSF significantly inhibits BHBN carcinogenicity (Irving et al, Cancer Res., 39, 3040, 1979), and, more recently DSF has been shown to inhibit the carcinogenicity of BCPN also (Proc. Am. Assoc. Cancer Res., 1981). The effect of DSF on the metabolism of these nitrosamines is under current investigation.